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Hydrobiologia

, Volume 583, Issue 1, pp 297–307 | Cite as

Disentangling the morphological stasis in two rotifer species of the Brachionus plicatilis species complex

  • Diego Fontaneto
  • Irene Giordani
  • Giulio Melone
  • Manuel Serra
Primary Research Paper

Abstract

The taxonomic uncertainty surrounding cryptic species complexes has traditionally been resolved using lengthy experimental approaches, while, since the advent of PCR based techniques the number of cryptic species described in a variety of taxa is increasing steadily. Here we formally describe a new rotifer species of the Brachionus plicatilis complex: Brachionus manjavacas n.sp., disentangling what was known as a morphological stasis. Detailed morphological analyses demonstrated significant differences in body shape and size between B. manjavacas and B. plicatilis s.s., analysed by geometric morphometrics; unfortunately these statistical differences are not taxonomically reliable because of wide overlaps. Size and asymmetry of masticatory apparatus, named trophi, observed by SEM, gave similar results, with taxonomic ambiguity. Only the shape of small pieces of the trophi, named satellites, were consistently different between the species. On a strictly classical taxonomical basis it is absolutely useful to name new species on morphological bases, as we did, and to assess their status as distinct entities. Nevertheless, the two species are broadly similar; therefore, we do not suggest using the small differences in shape of satellites of trophi to identify the species for further ecological studies, but to continue discriminating them on genetic marker bases.

Keywords

Brachionus manjavacas n.sp. Brachionus plicatilis Cryptic species Geometric morphometrics Scanning electron microscopy Trophi 

Notes

Acknowledgements

This work started during a visit by DF to the lab of MS, granted by the European Science Foundation in the framework of PARTNER Network. Subsequent funds came to GM from the Italian government, MIUR (project BIOSIMPA, Biodiversity of Inconspicuous Organisms in Spanish and Italian Marine Protected Areas), contract grant number: PRIN-2004057239_004. Scanning electron microscopy was done at CIMA. We thank Claudia Ricci for the use of her light microscopy facilities.

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Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • Diego Fontaneto
    • 1
  • Irene Giordani
    • 1
  • Giulio Melone
    • 1
  • Manuel Serra
    • 2
  1. 1.Dipartimento di BiologiaUniversità degli Studi di MilanoMilanoItaly
  2. 2.Institut Cavanilles de Biodiversitat i Biologia EvolutivaUniversitat de ValènciaValenciaSpain

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